Donal McBreen - Kamal 2.0: Deploy web apps anywhere - Rails World 2024

Kamal 2.0 is a modern deployment tool built for Docker, designed as a simpler alternative to Kubernetes for deploying web applications

Key features include:

• Zero-downtime deployments
• Asset bridging to handle static assets between deployments
• Built-in secret management with password manager integrations (1Password, LastPass, Bitwarden)
• Multi-app support on a single server
• Custom proxy solution optimized for container deployments

Core design principles:

• Imperative rather than declarative approach
• Minimal configuration required
• Fast deployment without polling/waiting
• No need for complex infrastructure

Requirements:

• Docker registry
• SSH access to deployment servers
• Docker installed on target hosts
• Domain pointing to server

Notable improvements in 2.0:

• Better secret management without storing secrets on disk
• Simplified asset handling between deployments
• More efficient proxy implementation
• Improved multi-app support
• Zero-config SSL/HTTPS support
• Built-in Rails console support

Will be included by default in Rails 8, making deployment significantly easier for new applications

Focuses on simple deployment scenarios:

• Single server deployments
• Small to medium applications
• Teams that don’t need/want Kubernetes complexity